Inadequate coverage is a persistent problem in the quality of service of any wireless network. Natural and man-made obstacles frequently create radio frequency (RF) holes in the coverage area of a wireless network. Voice and data call connections are frequently dropped when a wireless terminal, such as a cell phone or a similar mobile station, enters an RF hole. Mobile stations that are already in an RF hole may not be able to reliably establish new connections. Typical areas in which RF holes occur include homes, apartments, underground tunnels and office buildings.
Furthermore, wireless communication networks complimented by small base transceiver stations located to provide coverage in RF holes can frequently encounter coverage issues (e.g., interference from neighboring devices) that cause RF coverage holes. Even when such devices are configured to detect each other and adapt overall or directionally transmit power accordingly, interference may remain a problem.
For instance, a pair of small office or home office (SOHO) base transceiver stations in adjacent buildings may not detect each other due to outside wall penetration losses. A mobile or subscriber unit between or inside one of the two buildings, however, may detect both base transceiver stations even after taking into account factors such as distance, differences in interior versus exterior wall penetration losses, or both. Thus, the signal from the first SOHO base transceiver station (BTS) interferes with the signal from the second SOHO base transceiver station (BTS), or vice versa. This interference scenario is sometimes referred to as the hidden node problem.” Conventional adaptive interference controls for a SOHO BTS may provide for power control into a single antenna. For example, some adaptive interface controls currently use solitary dipole or monopole antennas. Such controls fail to provide selective reduction of transmitted RF power that could ultimately cause interference.
A SOHO BTS is typically placed within the confines of a SOHO and generally provides sufficient transmit power to overcome the attenuation of interior walls and floors. Often times, a SOHO BTS supplements a macrocell network where coverage is poor. Ideally, a SOHO BTS should operate without introducing significant interference to the external coverage environment. However, in practice, a SOHO BTS is often subjected to high interference.
In a code division multiple access (CDMA) environment, pilot strength (Ec/Io) is the ratio of received pilot energy (Ec) to total received energy or the total power spectral density (i.e., noise and signals) (Io) at the current CDMA frequency. Many systems known in the art report the number of pilots in an active set to a base station by a Power Measurement Report Message (PMRM), Pilot Strength Measurement Message (PSMM), Registration Message (RM) or similar. Currently, however, there is no system for analyzing pilot strength measurements to aid in tailoring the transmit power pattern to provide coverage in a small office or home office and minimize interference external to the small office or home office.
There is therefore a need for a system to manage power adjustments and minimize the impact of interference with a macroBTS or any neighboring SOHO BTSs and thereby greatly reducing interior coverage. Moreover, there is a need for providing wireless operators for limiting interference to wireless services external to the SOHO.